What is this Man Doing? Answered

Chuck Ditmars, the first lab manager for the Local Roads Program, taking the first of two readings for the Sand Equivalent test in 1955

Chuck Ditmars, the man in the photo on the right, is taking the first of two readings for the Sand Equivalent test. Chuck was the first lab manager and worked for the Local Roads Program for over 30 years from the 50’s into the 80’s.

The Sand Equivalent test is an alternative to the plasticity test for soils and is more applicable for many of the gravel bases and subgrades in New York State.

Sand Equivalent Test

The sand equivalent provides a measure of the cleanliness of an aggregate and the relative proportion of detrimental clay-like particles in the aggregate

Diagram showing the sand eqivalent test

The test is a scientific version of the old Mason jar test where you shake a bunch of gravel up and let it sit on the shelf overnight. Unlike the Mason jar test, the gravel sized particles are removed before testing. Like the Mason jar test, the test can be performed in the field in about 40 minutes

The material in the cylinder is allowed to soak; then it is shaken and allowed to settle for 20 minutes. Any sand in the mixture will settle out immediately, but the clay like portion will stay in suspension. The total height of the column is compared to the part that will support weight (see figure on the right). This ratio, known as the Sand Equivalent, gives a measure of the quality of gravel mixture. The recommended ranges, from NYSDOT Specification 667, are shown in the table below (along with other specifications for good gravel). Note that surface, base and subbase gravels have different specifications.

Test and control limits of gravel materials
Specification Item Surface Base Subbase
Maximum particle size
1 inch
2 inch
3 inch
Passing #200 sieve
(% by weight)
8-15
0-5
0-8
Passing #200 sieve
(% by weight)
20
20
25
Plasticity Index
2-9
0-5
0-8
Sand Equivalent
25-40
>40
>35

Resources

Sand Equivalent Test Tech Tip (PDF)

Local Road Gravel Material Specification Tech Tip (PDF)

NYSDOT Specification 667 (PDF)

Spring 2013

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This work by the Cornell Local Roads Program (CLRP) is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported License.